Treatment of phosphates.



. Decatur,

PATENT OFFICE.

NATHANIEL R mm, or DECATUR, GEORGIA, AssIenoR TO PRATT raocnss COM- PANY, or DECATUR, GEORGIA, A CORPORATION or GEORGIA.

TREATME T or, PHOSPHATES.

No Drawing.

Specification of Letters Patent;

Patented Jan. 9,1912.

Application filed July 5, 1911. Serial No. 637,025.

To a'lZ-whomit may concern:

Be it known that I, NATHANIEL P. PRATT, a citizen of the United States, I

in the county of Dekalb and State of Georgia, have invented certain new and useful Improvements in the Treatment of Phosphates, of which the following is a specification.

My invention relates to the treatment of phosphates.

In the broadest aspect of the invention, it resides in a method of treating phosphates containing sulfates which consists in separating the sulfates from the phosphates. 1

' In a more specificaspect, the lnvent-ion resides in a process of enrlching a phosphatic mass, contaming calcium *sulfate which is soluble in certain media and calcium phosphate which is insoluble in those media, which consists in subjecting said mass to the action of 'a suitable solvent to dissolve the sulfate, and then separating said sulfate-charged solution from the phosphate.

As is well known, in the manufacture of commercial acid phosphate, a mass contain-- ing a certain percentage of bone phosphate of lime, after fine grinding, is submitted to a given quantity and strength of sulfuric acid. The result of this admixture is substantially to reduce-the insoluble phosphate of lime to mono-calcic phosphate and free phosphoric acid. There, also, usually restilts a small percentage of di-calcic phosphate; but there remains no insolublebone phosphate of lime in said mass if the reaction in the mixture should be ideally comlete. I p It is well known that free phosphoric acid, and, also, the mono-calcic salt of the acid phosphate of commerce,.quickly revert to the citrate-soluble, or di-calcic form, when applied to the soil, and that, practically speaking, their agricultural value to the growing plant is not decreased after such reversion takes place.

In a commercial acid phosphate, such as described above, if the free phosphoric acid and the mono-calcicsalt are reverted to the di-calcic form-which can easily be done in any one of several ways, for instance, by the addition of a certain equivalent of finely-ground calcium carbonate-the agricultural value of the acid phosphate is not residing at in ammonium citrate water, for instance-the di-calcic ment of commercial acid phosphate, which usually carries in the neighborhood of sixty per cent. of calcium sulfate.

It also applies to tri-oalcium phosphate and native phosphates which have'been'tr eated with the necessary amount of sulfuric acid, and in the manner required,f0r the direct formationof the di-calcic salt and other phosphates insoluble in water but soluble solution. In the ,application thereto of certain solutions,-sea phosphate remains undissolved, and the calcium sulfate is dissolved, and may be eliminated in any suitable manner, the result of the elimination being to increase the percentage of di-calcic phosphate in an ordinary acid phosphate to an extent at least double.

Whenever a phosphatic-mass, is found'to embody, as one of its ingredients, a sulfate, such as calcium sulfate, m invention may be mostadvantageously utilized to separate the sulfate from the phos phate. It isa feature of my invention,- therefore, to separate the sulfate from the phosphate,-and this may be accomplished by subjecting a phosphatic mass containing sulfates and insoluble phosphates to the action of a sulfate-dissolving solution, and then eliminating, from the phosphates the resulting solution.

My invention is equally applicable to certain native phosphates with which'I have become familiar and which differ sub'stantially from other known native phosphates in at least two respects: first, they are not in the usual form of rock; and, secondly,. they include, as shown by analysis, about thirty-four per cent. (34%) of calcium sulfate, a proximately, and about sixty per cent. 60%),approximately, of bone phosphate of lime, the: last-mentioned being practically insoluble in water; The valuable constituent desired for the manufacture of commercial acid phosphate or fertilizers from such native material is bone phosphate of lime. By reason of the fact that these particular phosphates include practically no impurities, such as clay, sand, etc., in the sensethat such impurities usually exist in other native phosphates and which have to be taken into consideration in of any kind, v

other processes, I am enabled to utilize my" the cost of production, but the product obphosphate.

'tion to native phosphates containing sul-.

dNO. 604,998.

tained is exceedingly rich in its inclusion of amount of calcium-- This particular subject-matter a. desired proportionate is more specifically 7 described in mypending application, filed As is generally. known to those familiar with the art, native phosphates have hereto fore been prepared for use by washing wlth of flushing, this water The product application of my invenwater. By a system removes the sand and clay. resulting from the fates is distinguished from these 'so-called Washed phosphates,- as will readily be understood by those skilled in the art. I have found, by experiments, that the methods heretofore .practiced will not 'suflice to produce the best results native phosphates:

material is loose, light and earthy, and

. there are,- as already stated, none of the usual impurities, such I present; and, in the second place, the main, ,and practically the only,

as sand, clay, .etc

other than calcium phosphate, is calcium sulfate. It is desirable to remove this from 1 the phosphate because it is not a valuable fertilizer-ingredient. .It cannot, however, separatedthcrefrom at all by suspension in water like sand and clay, but, by experience,-

-Ihave discovered that it is soluble in fresh water.. It is more readily soluble in saline,

solutions, and, particularly, in thatclass of solutions comprising, or which includes, sea water'. I have also discovered that these and similar solvents have little or no practical action on the calcium phosphate pres- I cut in the mass.

For the treatment, of either the manufactured acid phosphate of commerce, or of other phosphates containingsulfates, or of native phosphates similar to those above described, I- subject said" phosphates to action ofa suitable solvent, suchas water, or a saline solution like sea water, or any of the known solvents, either lay treating the mater al, with the solvent and settling it out, and then eliminatingthe water to thereby carry. oif the sulfates insolution; or by percolation through the mass; or, in fact, by

- any other suitable means of treatment; the

- out of the masspresent.

object-being, to dissolve the sulfates and leave the phosphates The action of the' solvent, be. it fresh water, or a saline solution like sea water, or any other-appropriate solvent, is to dissolve the sulfates out of the phos'phatic' mass. I have found, by this novel method of solution and elimination, that the sulfatescan be removed, and with the practical always,

d, ay,

January 27th,"1911, Serial sulfate, is raised to a richness of approxiphate of lime. By my invention,

in connection with said In the first place, the

the .United Statesis: ingredient therein phosphates separating the result that, a mass of acid phosphate which,

for instance, contains eighteen per cent, (18%) of di-caclic phosphate is brought up to a richness of forty per cent. (40%) or more of di-calcic pho'sp ate; and a mass of native phosphate which contains, say, sixty per cent. (20%) of bone phosphate of lime,' t irty per cent (30%) of calcium mately ninety per cent. (90%) of bone phos- I am therefore enabled to utilize, with new results, solvents, such as water, saline solutions-- of which seawater furnishes apreferable typeand other solvents, to enrich phosphates insoluble in' said media but containing sulfates'soluble therein; and this process I claim broadly; 5

While I have herein described my new method in detail, it is to be understood'that I do not limit myself to such details of procedure, except in so far as these may be specified'inthe claims. 1 I I Having thus fully descr-ihed my invention, the procedure followed thereunder, and

the results produced,.what I claim as new and desire to secure by Letters-Patent, of

1. The method of treating mixtures of and sulfates, which-consists in by dissolving out the'sulfates and leaving thephosphates intact, orsubstantially so.

2. The method of treating phosphates containing sulfates, which consists in separating the sulfates from the phosphates, such separation being eife'ctedby subjecting the same the sulfates from the phosphates to the solvent action-of sea water and subsequently eliminatin containing the sulfate.

3. The method :of treating mixtures of phosphates insoluble in-water, and sulfates.

soluble therein, which consists in subjecting the same to the solvent action of-water to separate the sulfates from the phosphates,

from the mass'the water and ,theneliminating the water containing the sulfates.

.4, The method of treating mixtures of insoluble phosphatesand'calcium sulfate,

solvent action of a medium characterized by a sulfate-dissolving action, and eliminat-' ing from the phosphates the 'solution' produced.

5. The method of treating phosphates "'which'consists in subjecting the same to the,

containing sulfates which consists in subjecting the same to the solvent action of asaline solutlonto separate the sulfates from the phosphates, and then eliminating the sulfate-impregnated solution.

6. The method of treating phosphates containing sulfates which consists in sub- -jecting thesame to the solvent action of a saline solution including sea water to sep'a rate the sulfates from the phosphates, and

' then draining off the sulfate impregnated riching a cium phosphate by means of sea water, and

the phosphates.

sulfate and, as

9. The herein-described process of enriching a' phosphatic mass to approximately 90% bone phosphate of lime, which consists in subjecting native phosphates containing sulfates to the action of seawater and then separating the sulfate-containing water from the mass.

10. The herein-described process of treat-- ing native phosphates which, consists in removing the calcium sulfate from the calthen separating the sulfate solution from the phosphates which are insoluble in said at'er. 11. The method of treating a phosphatic mass containing, as one component, calcium another component, phossaid second-mentioned calcic form, and then separating thesulfate from the phosphate.

- mass containing,

and, as another component, phosphoric acid in anyform more acid than the 'di-basic salt, which consists'in reverting said secondmentionecl'component to the di-calcic form; then subjecting the mass to the solvent actionof a saline solution to separate the sulfates from I nating the sulfate-impregnated liquid;

' ghoric acid inany form more acid than the i-basic salt, which consists in reverting component to the di- 12. The method of treating a phosphatic mass containing as one component, calcium sulfate, and,

phoric acid in any form more acid than the di -basic salt, which consists in reverting said second-mentioned component to the dicalcic form solvent action of a medium characterized as another component, phosthen subjecting the mass to the a sulfate-dissolving action; and, then,

13. The method of treating a phosphatic as one component, sulfates,

the phosphates, and then elimi- In testimony whereof I aflix my signature in presence of two witnesses.

NATHANIEL P. PRATT. Witnesses:

ARTHUR J. WAND, EDMUND H. PARRY.

Copies 5% this patent may'be obtained for five cents each, by addressing the Commissioner of Patents,

- Washington,

- e iininating from the phosphates the resulting solution. 

